Study Of Iron Crystallization And Degradation Of Simulated Dye Wastewater In The Fenton Fluidized-bed Based On Modified Carrier

Nowadays,developing effective technologies for the treatment recalcitrant industrial wastewaters has attracted intensive attentions.Fenton system is one of the most promising technologies in advanced oxidation process（AOP）,and its deformation technology i.e.Fenton fluidized-bed process has already been applied in the large-scale industrial wastewater degradation.It combines the advantage of rapid mass transfer and oxidation rate with the advantage of reduction of iron sludge.However,the low iron removal efficiency is still the major barrier of the extensive use of the Fenton fluidized-bed.Therefore,in this study,a lab-scale Fenton fluidized-bed was established and investigated for the main operational parameters optimization including operating pH,expansion degree of the carriers,adding order of Fenton reagents,and loading capacity of carriers,based on the removal efficiency of dissolved iron species.Based on this,comparative study and modification of the different carriers were further conducted.A continuous Fenton fluidized-bed study for the degradation of simulated dye wastewater was then carried out by using the modified carriers.The main conclusion of this thesis are listed below:（1）According to the problem above,operational parameters were investigated to qualify their effects of Fe removal efficiency while the Fenton reagents concentration remain constant,namely C_Fe2+=1mmol/L,C_H2O2=20mmol/L.The optimized operational parameters were:pH=5,expansion degree at 50%,adding FeSO₄ firstly,and loading capacity at 300g,respectively.Moreover,the siliceous rock（carrier A）was proved to be the best carrier which achieved the highest Fe removal efficiency of the six.（2）Among all the calcined carrier A,the 600℃calcined carrier A achieved the highest Fe removal efficiency.Based on the results of XRD,XPS,FT-IR,and SEM methods,we concluded that the 600℃calcined carrier A had the loosest structure which resulted in the exposure of inner hydroxyl and the highest iron removal rate.The mechanism of iron crystallization is the bonding of hydroxyl on the carriers with the hydroxyl in Fe（OH）₃.Among all the iron-coated quartz sand,the calcined after iron-crystallized quartz sand enhanced the Fe removal efficiency by 30%.The process of coating iron oxides increased the amount of hydroxyl on quartz sand.As for carrier A,the iron-coated process didn’t improve its ability of iron crystallization.（3）Quartz sand,carrier A and B were all available for iron crystallization and simulated dye wastewater degradation in continuous Fenton fluidized-bed.Based on this,the 600℃calcined carrier A and calcined after iron-crystallized quarzt sand were applied in the continuous Fenton fluidized-bed as well.The COD removal efficiency of two process above were around 70%both,while the Fe removal efficiency were 70%and 20%,respectively.We concluded that the 600℃calcined carrier A was considered to be an ideal carrier in the continuous Fenton fluidized-bed which had good performance on both degradation of organics and removal of iron species.